Electron tomography of (In,Ga)N insertions in GaN nanocolumns grown on semi-polar (112̄ 2) GaN templates

We present results of scanning transmission electron tomography on GaN/(In,Ga)N/GaN nanocolumns (NCs) that grew uniformly inclined towards the patterned, semi-polar GaN( 11 2 ̄ 2 ) substrate surface by molecular beam epitaxy. For the practical realization of the tomographic experiment, the nanocolumn axis has been aligned parallel to the rotation axis of the electron microscope goniometer. The tomographic reconstruction allows for the determination of the three-dimensional indium distribution inside the nanocolumns. This distribution is strongly interrelated with the nanocolumn morphology and faceting. The (In,Ga)N layer thickness and the indium concentration differ between crystallographically equivalent and non-equivalent facets. The largest thickness and the highest indium concentration are found at the nanocolumn apex parallel to the basal planes

Electron tomography of (In,Ga)N insertions in GaN nanocolumns grown on semi-polar (11(2)over-bar2) GaN templates

We present results of scanning transmission electron tomography on GaN/(In,Ga)N/GaN nanocolumns (NCs) that grew uniformly inclined towards the patterned, semi-polar GaN( 112̄ 2 ) substrate surface by molecular beam epitaxy. For the practical realization of the tomographic experiment, the nanocolumn axis has been aligned parallel to the rotation axis of the electron microscope goniometer. The tomographic reconstruction allows for the determination of the three-dimensional indium distribution inside the nanocolumns. This distribution is strongly interrelated with the nanocolumn morphology and faceting. The (In,Ga)N layer thickness and the indium concentration differ between crystallographically equivalent and non-equivalent facets. The largest thickness and the highest indium concentration are found at the nanocolumn apex parallel to the basal planes

Distinguishing cubic and hexagonal phases within InGaN/GaN microstructures using electron energy loss spectroscopy

3D InGaN/GaN microstructures grown by metal organic vapor phase epitaxy (MOVPE) and molecular beam epitaxy (MBE) have been extensively studied using a range of electron microscopy techniques. The growth of material by MBE has led to the growth of cubic GaN material. The changes in these crystal phases has been investigated by Electron Energy Loss Spectroscopy, where the variations in the fine structure of the N K‐edge shows a clear difference allowing the mapping of the phases to take place. GaN layers grown for light emitting devices sometimes have cubic inclusions in the normally hexagonal wurtzite structures, which can influence the device electronic properties. Differences in the fine structure of the N K‐edge between cubic and hexagonal material in electron energy loss spectra are used to map cubic and hexagonal regions in a GaN/InGaN microcolumnar device. The method of mapping is explained, and the factors limiting spatial resolution are discussed

Polymer functionalized gold nanoparticles as non-viral gene delivery reagents.

Background: In this study we investigated the ability of PEG functionalized gold nanoparticles as non-viral vectors in the transfection of different cell lines, comparing them with commercial lipoplexes. Methods: Positively charged gold nanoparticles were synthesized using PEI as reducing and stabilizer agent and its cytotoxicity reduced by its functionalization with PEG. We bound the nanoparticles to three plasmids with different sizes (4-40 kpb). The vector internalization was evaluated by confocal and electronic microscopy. Its transfection efficacy was studied by fluorescence microscopy and flow cytometry. The application of the resulting vector in gene therapy was indirectly evaluated using ganciclovir in HeLa cells transfected to express the herpes virus thymidine kinase. Results: An appropriate ratio between the nitrogen from the PEI and the phosphorous from the phosphate groups of the DNA together with a reduced size and an elevated electrokinetic potential are responsible for an increased nanoparticle internalization and enhanced protein expression when carrying plasmids of up to 40kbp (plasmid size close to the limit of the DNA carrying capacity of viral vectors). Compared to a commercial transfection reagent, an equal or even higher expression of reporter genes (on HeLa and HEK 293T) and suicide effect on HeLa cells transfected with the herpes virus thymidine kinase gene were observed when using this novel nanoparticulated vector. Conclusions: Non-viral vectors based on gold nanoparticles covalently coupled with polyethylene glycol (PEG) and Polyethylenimine (PEI) can be used as efficient transfection reagents showing expression levels same or greater than the ones obtained with commercially available lipoplexes.pre-print3905 K

Study of Melamine-Formaldehyde/Phase Change Material Microcapsules for the Preparation of Polymer Films by Extrusion

n-Eicosane-melamine formaldehyde microcapsules of an average size of 1.1 µm and latent heat of fusion of 146.2 ± 5.3 J/g have been prepared. They have been characterized by scanning electron microscopy, FTIR spectroscopy, calorimetric techniques, and thermogravimetric analyses. Under processing conditions, the microcapsules apparently preserved their properties, also maintaining their n-eicosane loading and heat storage capacity under washing conditions (water with detergent at 60¿C). The microcapsules synthesis has been scaled up for the fabrication of functional films by extrusion. For that, polymer films containing 10 wt.% of microcapsules were prepared at a pilot plant level. In those films, even though a fraction of the n-eicosane loading was lost during the extrusion process, the microcapsules showed good compatibility within the polyamide. The percentage of PCM in the polyamide 6 films was estimated by TGA, verifying also the heat storage capacity predicted by DSC (2.6 ± 0.7 J/g). © 2022 by the authors. Licensee MDPI, Basel, Switzerland

Endangered subspecies of the reed bunting (Emberiza schoeniclus witherbyi and E. s. lusitanica) in Iberian Peninsula have different genetic structures

In the Iberian Peninsula, populations of two subspecies of the Reed Bunting Emberiza schoeniclus have become increasingly fragmented during the last decades when suitable habitats have been lost and/or the populations have gone extinct. Presently, both subspecies are endangered. We estimated the amount of genetic variation and population structure in order to define conservation units and management practices for these populations. We found that the subspecies lusitanica has clearly reduced genetic variation in nuclear and mitochondrial markers, has a drastically small effective population size and no genetic differentiation between populations. In contrast, the subspecies witherbyi is significantly structured, but the populations still hold large amounts of variation even though the effective population sizes are smaller than in the non-endangered subspecies schoeniclus. We suggest several management units for the Iberian populations. One unit includes subspecies lusitanica as a whole; the other three units are based on genetically differentiated populations of witherbyi. The most important genetic conservation measure in the case of lusitanica is to preserve the remaining habitats in order to at least maintain the present levels of gene flow. In the case of the three management units within witherbyi, the most urgent conservation measure is to improve the habitat quality to increase the population sizes.This project would not have been possible without the help of many people, among them A. Rodriguez, D. Bigas, P. Vicens, J. Segura, M. Suarez, J. L. Martinez, V. Urios, M. Rebassa, C. Torralvo, J. L. Hernandez, M. Carregal, P. Alcazar, J. L. Canto, J. Ramirez,, D. Alonso, J. Arizaga, F. Arcos, H. Rguibi, Acciona-Trasnmediterranea, and many others who helped us with the difficult task of sampling Reed Buntings and who sent us their samples. We apologize if we have forgotten someone. "Arcea Xestion de Recursos Naturais S. L." was of inestimable value in obtaining most of the samples from Galicia in 2008, in getting funding from the "Xunta de Galicia", and in helping us with the discussion of the results. We would like to thank the authorities of Daimiel National Park, Marjal Pego-Oliva Natural Park, S'Albufera de Mallorca Natural Park, Delta de L'Ebre Natural Park, "Consejeria de Medio Ambiente y Desarrollo Rural de Castilla La Mancha", "Servicio de Conservacion de la Diversidad del Gobierno de Navarra", "Direccion Xeral de Conservacion da Natureza de la Xunta Galicia and "Servei de Conservacio de la Biodiversitat de la Generalitat Valenciana" for the facilities to work in protected areas and for the appropriate permits to obtain the samples. The people from these protected areas were always very nice and helped us with the fieldwork. This study was funded by projects CGL2005-02041/BOS of the "Ministerio de Educacion y Ciencia" of Spain, and SC000207, Orden 14-12-2005 of the "Consejeria de Medio Ambiente y Desarrollo Rural de la Junta de Castilla La Mancha", Spain, through the "Ayudas para la realizacion de actuaciones de apoyo a la conservacion de las areas y recursos naturales protegidos, Orden 14-12-2005". The "Direccion Xeral de Conservacion da Natureza de la Xunta de Galicia", Spain, funded part of the fieldwork in NW Iberian Peninsula during the development of the Recovery plan for Emberiza schoeniclus lusitanica in Galicia. The experiments comply the current laws of the countries (Spain, Portugal and Finland) where they were done.Kvist, L.; Ponnikas, S.; Belda Perez, EJ.; Encabo, I.; Martinez, E.; Onrubia, A.; Hernandez, JM.... (2011). Endangered subspecies of the reed bunting (Emberiza schoeniclus witherbyi and E. s. lusitanica) in Iberian Peninsula have different genetic structures. 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The effect of hollow gold nanoparticles on stem cell migration. Potencial application in tissue regeneration.

Every year trauma together with bone, joints and cartilage-associated diseases usually involve structural damage, resulting in a severe pain and disability for millions of people worldwide[1]. In regenerative medicine, cellular, tissue and organ-based approaches are developed to restore biological functions that have been lost[2],[3]. Therefore, tissue repair and regenerative medicine have attracted the interest of the scientific community, providing promising results in preclinical models and clinical pilot studies.pre-print3341 K

Human Erythroid Progenitors Are Directly Infected by SARS-CoV-2: Implications for Emerging Erythropoiesis in Severe COVID-19 Patients

We document here that intensive care COVID-19 patients suffer a profound decline in hemoglobin levels but show an increase of circulating nucleated red cells, suggesting that SARS-CoV-2 infection either directly or indirectly induces stress erythropoiesis. We show that ACE2 expression peaks during erythropoiesis and renders erythroid progenitors vulnerable to infection by SARS-CoV-2. Early erythroid progenitors, defined as CD34-CD117+CD71+CD235a-, show the highest levels of ACE2 and constitute the primary target cell to be infected during erythropoiesis. SARS-CoV-2 causes the expansion of colony formation by erythroid progenitors and can be detected in these cells after 2 weeks of the initial infection. Our findings constitute the first report of SARS-CoV-2 infectivity in erythroid progenitor cells and can contribute to understanding both the clinical symptoms of severe COVID-19 patients and how the virus can spread through the circulation to produce local inflammation in tissues, including the bone marrow

Selective delivery of photothermal nanoparticles to tumors using mesenchymal stem cells as Trojan horses

The main challenge of cancer treatment is to avoid or minimize systemic side effects in off-target tissues. Mesenchymal stem cells (MSCs) can be used as therapeutical carriers because of their ability to migrate and incorporate into inflammation areas including tumors. Here, this homing ability is exploited by carrying therapeutic nanoparticles (Hollow Gold Nanoparticles (HGNs)) following a “Trojan-horse” strategy. Amongst the different nanoparticles to be employed, HGNs have the capacity to resonate in the near infrared region when irradiated by an appropriated laser (808 nm). By transforming this absorbed energy into heat, they are capable to produce locally induced hyperthermia. At this wavelength healthy tissues have a minimal light absorption being the effect restricted to the tissues containing HGNs. By placing HGNs inside MSCs, the recognition, excretion and immune response are minimized. We demonstrate that MSCs internalize HGNs and reach the tumors still containing HGNs. After laser treatment this loaded cells are able to eradicate tumoral cells in vitro and in vivo without significant toxicity. Also Ki67 expression, which is usually correlated with proliferation, is reduced after treatment. This approach enhances the effectiveness of the treatment when compared to just the enhanced permeation and retention effect (EPR) of the HGNs by themselves